Spectacle.

Different shortcuts for different things.

Your shortcut, or just PrtSc does the default thing (configurable in Preferences).
Meta + Shift + Print = Rectangular region
Shift + Print = Fullscreen
Meta + Print = Active window
Meta + Ctrl + Print = Select window
Options include:
Include mouse pointer
Include window titlebar and borders
Include window shadow
Quit after manual save or copy
Delay